This disclosure relates to a method of forming trenches employing a manganese oxide hard mask layer and structures formed by the same.
Hard mask erosion limits parameters of anisotropic etch processes, and particularly, the depth of a trench that can be formed by the anisotropic etch processes. The erosion of hard mask is particularly problematic if the etched material is a dielectric material. For example, a hard mask including silicon oxide tends to be etched at a significant rate while etching a silicon-oxide-containing material such as organosilicate glass (OSG) and doped silicate glass. Hard mask erosion can induce widening of a trench at an upper portion, thereby causing formation of a tapered trench. Further, when such a tapered trench is filled with a conductive material, for example, in order to form a through substrate via (TSV) structures, the resulting conductive structure includes a tapered portion at which the conductive structure occupies more area than a lower portion making contact with a contact pad.
In view of the above, a method for forming a trench through a thick dielectric material with no, or minimal, erosion of a hard mask material is desired.